Reserpine-induced mobilization of histamine and vitamin B 12-binding proteins from a special type of endocrine cells in rat stomach

Abstract

Reserpine was found to mobilize histamine from a large number of the enterochromaffin-like cells in the oxyntic gland area of the rat stomach, as revealed by fluorescence histochemistry. Chemical estimations demonstrated a 50 per cent reduction in the gastric histamine content upon reserpinization. Histamine persisted in gastric mast cells and in a population of reserpine-resistant enterochromaffin-like cells. The results indicate the existence of three separate pools of gastric histamine. Vitamin B 12-binding proteins (including the intrinsic factor) have been suggested to occur in the histamine-containing enterochromaffin-like cells of the rat stomach. Reserpine treatment caused an almost total depletion of gastric vitamin B 12-binding proteins, whereas the intrinsic factor activity (i.e. the ability to absorb ingested [ 58Co] labelled cyanocobalamin) was only moderately impaired. It is suggested that the vitamin B 12-binders reside in the reserpine-sensitive population of enterochromaffin-like cells, and that also under conditions of impaired storage, the formation and continuous release of intrinsic factor is sufficient to satisfy the normal demands of vitamin B 12 absorption.